Summary of Work: The substantial advancements in TAR cloning in the Chromosome Stability Group provided for development of a separate, independent Gene Isolation Unit that devotes much of its efforts to refining TAR cloning approaches for mammalian tissues. We initiated a collaboration with Ron Walter, Southwest Texas University, to develop yeast artificial libraries (YAC) from the fish Xiphophorous, since these fish are excellent whole animal genetic models for DNA repair and tumor suppressor control. We have also started the isolation of regions surrounding specific genes where known tumor suppressor genes have been mapped (Xmrk and Cdkn2 regions). TAR cloning of cDNAs is being refined to examine expressed genes from various cancer tissues using our yeast functional assays. In other studies we have shown that TAR cloning of p53 cDNA from human cell lines and cancer tissue is an accurate process and that yeast-based systems can be used to characterize mutant p53s. Based on the results of the TAR cloning of the human p53, we have initiated a project to clone and test the p53 from Xiphophorous, and then to test p53's from different induced tumors in our yeast based system.